1. Introduce yourself
I am Antti Karilainen, Principal Engineer at CoreHW. I work with our RTLS business and Design Service projects. In addition to RTLS product engineering, my specialization is electromagnetic modeling, antenna design, and microwave design.
In practical terms, my work is about making sure the wireless measurement behind a real-time location system is physically reliable before the data reaches the position engine. In Bluetooth Angle-of-Arrival RTLS, that starts with the tag antenna, the locator antenna array, the RF path, and the way the product is designed for real use.
2. In RTLS projects, how often do accuracy and reliability issues actually originate from antenna design rather than software or algorithms?
I would not reduce RTLS accuracy to one component, but many issues that appear as software or algorithm problems actually begin earlier in the physical radio channel.
RTLS devices work wirelessly in the same 2.4 GHz environment as other Bluetooth and Wi-Fi devices. An open warehouse or outdoor space behaves very differently from a hospital, office, or industrial environment with corridors, walls, people, equipment, storage racks, and large machines. Bluetooth AoA accuracy depends heavily on line-of-sight signal paths and good signal-to-noise ratio. The locator antenna arrays must receive signals from the directions where accurate positioning is needed, and the tags must transmit in a way that gives one or more locators a usable direction-finding signal.
This is why antenna design is often one of the first places to look when accuracy changes between a lab test and a real deployment. A tag may be worn on a wrist, carried on a lanyard, attached to equipment, mounted on a metal crate, or placed inside a plastic or cardboard box in a random orientation. Locators may be installed on different surfaces and may also rely on network backhaul such as Wi-Fi or Ethernet. If the antennas are not designed and characterized for these realities, the software receives lower-quality measurements. Filtering can help, but it cannot fully replace a clean RF measurement.
3. What constraints in small devices (tags, locators) most often limit antenna performance, and how do they show up in real deployments?
The biggest constraint is that the antenna has to work inside a product that people and assets actually use. In small battery-powered devices, antenna performance is affected by product size, enclosure materials, battery placement, mounting method, the human body, metal surfaces, and tag orientation.
Antenna performance is only strong when it is designed into the product from the beginning. A wearable tag is generally not the same RF problem as a fixed asset tag. CoreRTLS personnel tags are physically optimized for wrist-worn and lanyard use cases, while the asset tag is optimized for fixed mounting. That matters because of the antenna pattern, radiated efficiency, and the probability of a useful signal path change with how the tag is used.
In real deployments, a poor antenna fit typically appears as lower received signal level, unstable angle estimates, shorter effective range, or the need for a denser locator installation. While the system can still function, reduced RF performance cannot be entirely compensated for through increased infrastructure, careful antenna placement, or conservative configuration settings.
4. What do RTLS teams most often get wrong about antennas, and what does that typically cost them in practice?
The most common mistake is treating antennas as interchangeable components rather than as a critical element of the RTLS infrastructure.
On the locator side, Bluetooth AoA depends on the antenna array. The system calculates the directions from signals received across multiple antenna elements, so array geometry, phase behavior, switching, and characterization all matter. The CHW1010-ANT2 reference module uses sixteen patch antenna elements, a CHW1010 SP16T antenna switch, optimized phase balance between antenna chains, and defined RF/control connections. Therefore, an AoA antenna array is not a generic antenna; it contributes directly to location accuracy and reliability.
If the antenna array is not properly characterized, systematic angle errors will appear. One direction may produce good angle estimates while another direction produces biased or inconsistent results. In practice, that means more troubleshooting, less predictable coverage, reduced trust in the location output, and often more locators than originally planned.
On the tag side, the mistake is assuming one standard antenna implementation will fit every use case. A tag antenna that works well on a lanyard may not be the right fit when the tag is mounted on metal, attached to equipment, or placed inside packaging. The cost is usually paid later in bad accuracy and battery-life trade-offs.
5. What are the most common misconceptions about Bluetooth-based RTLS technologies, and how do they impact system performance?
One of the most common misconceptions is treating all Bluetooth positioning technologies as if they deliver the same level of performance. Legacy Bluetooth positioning based primarily on received signal strength (RSSI) is fundamentally different from Bluetooth Angle-of-Arrival (AoA).
With Bluetooth AoA, the locator uses an antenna array to measure the direction of incoming signals rather than simply estimating distance from signal strength. This makes antenna design, antenna array characterization, phase consistency, and I/Q signal quality critical factors in overall system performance.
As a result, achieving reliable, high-accuracy positioning is not only a software challenge. The underlying RF and antenna architecture are integral parts of the positioning system itself. When these elements are designed correctly, Bluetooth AoA can deliver significantly higher accuracy and robustness in demanding real-world environments.
6. In challenging environments like metal-heavy or industrial sites, what are the key antenna design trade-offs you cannot avoid, and how do they impact system performance?
Metal-heavy and industrial sites force RF design and deployment planning to work together. Conductive walls, machines, storage racks, equipment, and mounting surfaces change how signals propagate. They can block line of sight, create reflections, and make the antenna behave differently than it would in free space.
The unavoidable trade-off is between compact, durable product design and antenna behavior that remains stable near real mounting surfaces. Tags and locators need antennas that tolerate the environment, including conductive surfaces, without losing the signal quality required for reliable angle estimation.
This affects system performance directly. If the antenna does not tolerate the installation environment, the deployment may need more locators, shorter tag-to-locator distances, or adjusted mounting positions. Industrial and healthcare environments may require devices to withstand dust, UV exposure, and wide temperature ranges, while also supporting sanitization, waterproofing, and skin-friendly materials.
7. When do power efficiency and latency become real limiting factors in RTLS deployments, not just theoretical concerns?
Power efficiency and latency become real constraints when many tags are moving in the same area, and the system is expected to show real-time movement.
The best user experience comes when moving tags transmit positioning packets frequently enough for low-latency tracking. The trade-off is that the 2.4 GHz radio channel is shared and limited. If many tags transmit as fast as possible at the same time, packets can be lost and locators may not be able to track every tag reliably. At the same time, battery-powered tags drain faster.
This is why motion-aware behavior matters. Tags include an accelerometer that can detect movement. When a tag is stationary, it can remain in lower-power modes; when it is moving, it can use faster intervals for high-accuracy, low-latency motion tracking. The goal is not maximum transmission all the time. The goal is the right transmit intervals and transmit power for the current situation, while balancing reliability, latency, system capacity, and battery life.
8. Can software realistically compensate for poor RF design?
Software can help, but only up to a point.
A position engine can compute, filter, smooth, and reject poor measurements. CoreRTLS Software receives direction-finding data from locators, computes 3D position estimates, and applies filtering to improve accuracy and stability. But software is downstream of RF measurement.
If the antenna pattern is unsuitable, the locator array is poorly characterized, or the tag signal is weak because of mounting, orientation, or the surrounding material, the software receives a compromised measurement. It may reduce visible noise in the position estimate, but it cannot fully compensate for information that was not captured accurately in the first place.
For excellent RTLS performance, strong RF design and strong software have to work together. Hardware reduces errors before software starts; software then turns reliable measurements into stable location output.
9. Where will antenna design create the biggest competitive advantage in RTLS over the next few years, and why?
Antenna design will create competitive advantage where RTLS systems have to move from controlled demonstrations to scalable real deployments.
In a real deployment, the differentiator is not only whether the system can show a location point. It is whether the system can keep producing reliable, low-latency, high-confidence positions when tags are worn differently, assets are mounted on different materials, people move through the radio path, and many devices share the same area.
That advantage comes from designing the full stack together: ICs, antenna, tag, locator, firmware, position engine, APIs, and lifecycle management. CoreRTLS is positioned as a complete system of tags, locators, and software. The locator includes an optimized 16-element antenna array, tags use CoreHW antenna technology, and the software processes direction-finding data through a Position Engine with MQTT and REST interfaces for integration.
My view is that antenna and RF design are the bedrock of accurate RTLS. Software and algorithms are essential, and they perform best when the physical layer gives them high-quality measurements. That is why antenna design remains one of the hidden differentiators between robust, accurate deployments and mediocre ones.
About Antti Karilainen
Antti Karilainen is Principal Engineer at CoreHW, specializing in antenna engineering, electromagnetic modeling, and wireless system design. With more than 15 years of R&D experience spanning both industry and academia, he plays a key role in the development of CoreHW’s Bluetooth® AoA RTLS solutions. His expertise covers antenna arrays, RF systems, microwave engineering, and semiconductor technologies, with a particular focus on translating advanced RF design into reliable, high-accuracy real-world positioning performance.